Class 9 Science Formulas Handbook (Chapter-wise)

Every key fact and formula from the Class 9 Science NCERT syllabus, organised by chapter, in one place. Cross-linked to our full Chapter-wise Solutions. More chapters will be appended here as their Solutions are published.

Class 9 Science Formulas Handbook

Chapter 1: Matter in Our Surroundings

• Temperature conversion: K = °C + 273; °C = K − 273
• States of matter order (density, usually): solid > liquid > gas
• Interparticle force order: solid > liquid > gas
• Kinetic energy order: gas > liquid > solid
• State changes: fusion (solid→liquid), vaporisation (liquid→gas), condensation (gas→liquid), solidification (liquid→solid), sublimation (solid→gas), deposition (gas→solid)
• Factors increasing evaporation rate: higher temperature, larger surface area, higher wind speed, lower humidity
• See full Chapter 1 Solutions

New Syllabus (Exploration, 2026-27)

Chapter 1: Entering the World of Secondary Science

• Scientific method: observation → hypothesis → testing → model/theory.
• Law: mathematical pattern (e.g. Newton’s laws); Theory: well-substantiated explanation.
• SI units standardise measurement; estimation aids reasoning.

Chapter 2: Cell: The Building Block of Life

• Prokaryotic (no nucleus) vs Eukaryotic (true nucleus).
• Plant-only: cell wall, large vacuole, chloroplast.
• Mitochondria: powerhouse; Mitosis: 2 identical cells; Meiosis: 4 gametes, half chromosomes.

Chapter 3: Tissues in Action

• Plant: Meristematic (growth) vs Permanent (specialised).
• Animal: Epithelial, Connective, Muscular, Nervous.
• Tendon: muscle-bone; Ligament: bone-bone.

Chapter 4: Describing Motion Around Us

• v = u + at; s = ut + ½at²; v² = u² + 2as.
• Position-time slope = velocity; Velocity-time slope = acceleration, area = displacement.

Chapter 5: Exploring Mixtures and their Separation

• Solution (dissolved) < Colloid (Tyndall effect) < Suspension (settles).
• Techniques: crystallisation, distillation, chromatography, sublimation, centrifugation, coagulation.

Chapter 6: How Forces Affect Motion

• Newton 1: inertia; Newton 2: F=ma; Newton 3: action-reaction (different bodies).

Chapter 7: Work, Energy and Simple Machines

• W = F×d; KE = ½mv²; PE = mgh; P = W/t.
• Mechanical advantage = load/effort.

Chapter 8: Journey Inside the Atom

• Thomson (plum pudding) → Rutherford (nucleus) → Bohr (shells).
• Shells: 2n² (K=2, L=8, M=18); Isotopes: same element, diff mass; Isobars: diff element, same mass.

Chapter 9: Atomic Foundations of Matter

• Conservation of Mass, Constant Proportions → Dalton’s theory.
• Ionic (transfer e-) vs Covalent (share e-); criss-cross method for formulae.

Chapter 10: Sound Waves: Characteristics and Applications

• Longitudinal wave; needs medium; v = λf.
• Frequency → pitch; Amplitude → loudness; Echo needs ≥17m.

Chapter 11: Reproduction: How Life Continues

• Pollination → Fertilisation → Seed/Fruit; Seed dispersal.
• Human: testes/ovaries, fertilisation in fallopian tube, ~28-day menstrual cycle.

Chapter 12: Patterns in Life: Diversity and Classification

• 5 Kingdoms: Monera, Protista, Fungi, Plantae, Animalia.
• Binomial nomenclature: Genus + species (italicised).
• Viruses: acellular, living/non-living boundary.

Chapter 13: Earth as a System: Energy, Matter and Life

• 5 Spheres: Geo, Hydro, Atmo, Cryo, Bio.
• Cycles: Water, Carbon, Nitrogen, Oxygen.

Written by Satish

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